I'm testing vfiler migrations as well on 8.2 and getting the same error. I've found a couple of mentions that even though sync and semi sync snapmirror are included in the snapmirror license you need to add a special free one. I found it here:
Even though the release notes state that 5.3 now supports the licensing changes to ONTAP 8.2 it didn't. Once the plugin was installed and I refreshed the system via Ops Mgr the Management console correctly reported the 8.2 systems' licensing. However it failed on something else, differing disk types ATA to FSAS.
In the end I pre-created the required vols on target system, didn't restrict them and then ran:
this worked even with an open file and a script constantly writing to a 3GB file @ 120MB/s so as long as the NFS timeouts are long enough (we're NFS shop) there's just a pause rather than and down time